In watches with a seconds wheel and in particular electronic watches provided with a stepping motor, it is noted that the seconds hand oscillates at the end of a motor pulse and stops elsewhere than directly opposite the indices on the dial. This phenomenon is due to the play in the gearing. It is encountered in particular in watches where the motor drives the seconds wheel through one or several intermediate wheels. One finds a similar behaviour in mechanical watches of the type referred to as indirect center seconds. In order to eliminate such unaesthetic operation, it has already been proposed to provide a brake on the seconds wheel. Usually, this brake is obtained by means of a spring working on the end of a pivot. Unfortunately, such an arrangement takes up space in the thickness of the watch. Presently the thickness of watches is an important parameter and this solution is therefore no longer practicable.
It has likewise been proposed to obtain mechanical braking by placing a magnet in the neighborhood of the axle of the seconds wheel in a fashion to increase the rubbing force of this wheel turning in its bearing. This solution likewise leads to the difficulty of requiring space in the thickness.
In one case as in the other, the pivoting of the seconds wheel is lubricated. Consequently, the friction is above all of the viscous type,. i.e. increasing as a function of the speed.
There results therefrom a considerable increase of the braking couple during driving of the wheel train for a very small increase in the positioning couple. It can thus be said that energy consumption increases in a substantial manner for a small result.
The purpose of the invention is to obtain a wheel train brake which requires no additional space in the thickness of the timepiece and generating a braking couple assuring a good positioning of the seconds hand without any noticeable increase in the consumption of energy.